1. Field of the Invention
The present invention relates to a camera apparatus equipped with an automatic focusing control function, and/or an automatic exposure control function.
2. Description of the Related Art
Recently, most of the camera apparatuses are equipped with either an automatic focusing control function, or an automatic exposure control function, or with both functions.
In such an automatic focusing control function, a focusing area is defined at a central part within a viewfinder, and then a focusing control is performed with respect to a viewed subject within this focusing area.
Furthermore, a so-called "focusing lock function" is provided with the automatic focusing control function. In accordance with the focusing lock function, a photograph focused on a subject which should be focused can be obtained even if this subject is not positioned within the focusing area while viewing the image through the viewfinder.
That is, this focusing lock function is performed as follows. Even when a change occurs in the once focused subject positioned within the focusing area, the lens position set to obtain the focused subject is locked without performing a further focusing function. In general, the focusing lock function is operable when the release switch is held under such a condition that this switch is depressed over a half travel length thereof, or the focusing lock switch is depressed.
In, on the other hand, the automatic exposure control function, the light quantity of the entire subject is generally measured so as to perform the exposure control.
When the focusing lock function is not equipped with the camera apparatus, the subject to be focused must be continuously positioned on the center of the viewfinder in order to perform the above-described automatic focusing control function, since the focusing area is fixed. Accordingly, such a camera apparatus has a drawback that a freedom on designation of an image is restricted. Furthermore, even if the automatic focusing control function is performed in conjunction with the focusing lock function, cumbersome operations are required, resulting in the incorrect operation of the camera apparatus. Also, in a still camera, there is another drawback that a lengthy photographing operation is required.
Furthermore, the above-described conventional automatic exposure control function has the following drawbacks. That is, in case that a dark portion and a light portion, the luminance of which is extremely different from that of the dark portion, are present within an overall subject to be photographed, the exposure control is executed based upon an average value of the respective luminance. As a consequence, the resultant image has different luminance from the respective luminance of both the dark and light portions. In particular, the above-described problem is emphasized when an image requiring the optimum luminance is positioned at either the dark portion, or the light portion.